1. Field of the Invention
The present invention relates to an electronic switching system connected to an external computer and thereby enabled to be controlled by this computer.
2. Description of the Prior Art
A conventional electronic switching system such as a private branch exchange (PBX) provides its users with various services by the use of internally stored programs in addition to its principal function of telephone switching. For instance, a switching system described in the Australian Patent AU-B-46699/85 controls various services with a computer (service processing unit) provided within a switching apparatus.
Meanwhile, along with the diversification of such services, there are increasing requirements for processing large quantities of data over many hours. Among known electronic switching systems designed to meet these requirements, there is one which causes a built-in service processing unit to send information to an external processing unit, which processes that information, and to execute the service functions, with the results of processing returned from the external processing unit.
Referring to FIG. 1 such a switching apparatus 800 has a telephone terminal interface 811, an information receiver 812, a state controller 813, a data memory 814, a computer interface 815 and a service processing unit 816.
The terminal interface 811 connects a telephone terminal 820 by way of a telephone line 82 and transfers, for instance, push-button information from the terminal 820 to the information receiver 812 or, conversely, display information for a lamp or character display to the terminal 820 from the state controller 813. In the data memory 814 is stored, for example, subscriber information.
The computer interface 815 connects an external computer 90 through a dedicated line 83, and links information to be transferred between the service processing unit 816 and the computer 90 by a prescribed way of conversion.
The service processing unit 816, receiving a demand for service processing, for instance, through the information receiver 812 in response to functional push-button information from the terminal 820, demands required information, by the use of the program for the demanded service, from the state controller 813 and the data memory 814, receives that information, and thereby executes processing of the information. The switching apparatus 800, as its information processing capacity and information storage capacity are limited, has the computer 90 execute the kind of processing which permits the use of a general-purpose program or processing which takes a long time to accomplish, or store a large quantity of information resulting from processing. The computer 90 receives information from the line 83, processes it, transmits prescribed resultant information and, at the same time, stores prescribed information.
This procedure will be described now with reference to FIGS. 1 and 2 together.
First, when one of the service functions is designated (step S51) with a functional button on the terminal 820, the information receiver 812 receives the service designation via the interface 811, identifies the kind of service designated and correspondingly drives the service processing unit 816 (step S52). The unit 816 transmits state control information to the terminal 820 via the state controller 813 and the terminal interface 811, and demands information required for service processing by displaying a message on the character display of the terminal 820 (step S53). The user pushes the proper button(s) in accordance with the displayed message. In response to the sending of push-button information from the terminal 820 (step S54), this information is transferred to the service processing unit 816 (step S55) to undergo processing (step S56). When processing by the computer 90 is temporarily needed in the middle of service processing, the service processing unit 816 transmits the processing demand to the computer 90 via the interface 815 and the line 83 (step S57) to actuate an information processing unit (step S58). The computer 90, having accepted this processing demand, transmits demand acceptance information to the switching apparatus 800 (step S59). Upon receipt of the demand acceptance information, the service processing unit 816 makes ready the information to be processed (step S60) and transfers it to the computer 90 (step S61). The computer 90 processes the received information (step S62), stores necessary information, and reports the result of processing to the service processing unit 816 by way of information transfer (step S63). The service processing unit 816 further processes the received result (step S64) to complete service processing, and reports the result on the character display of the terminal 820 (step S65). As the satisfied user presses the service disengagement button (step S66), the service processing unit 816 receives a service disengagement demand (step S67), disengages the service designation (step S68) and reports the disengagement to the terminal 820 (step S69).
Having received the result report at step S63, the service processing unit 816 demands the computer 90 to disengage (step S70), causes it to release the processing unit (step S71) and receives the report of disengagement (step S72). To sum up, the prior art system, even though using an external computer, uses the computer merely as an external memory or for auxiliary processing.
Since the electronic switching apparatus by the prior art has within itself a service processing unit for the execution of various service functions, the software structure of the switching apparatus, as illustrated in FIG. 3, has integrated the basic program for performing various basic functions of the switching apparatus (including dial/key information discrimination and network switch connection) and various application programs for the extra service functions. Therefore, addition or alteration of any service function would require revision of all the software used for the switching apparatus. Furthermore, since every user has different requirements, the software has to be tailored to individual users' needs, resulting in the disadvantage that the switching system cannot be standardized.